Avalanche photodiodes (APDs) have been widely used in telecommunication, military, imaging, and research applications. Compared to p-i-n photodiodes, APDs have higher sensitivity owing to the multiplication gain. However, the gain, which originates from impact ionization, is also the source of noise for which the figure of merit is the excess noise factor F(M). In the local field model, the excess noise factor can be expressed as: F (M) = kM +(1?k)(2?1/M), where k is ratio of the hole ionization coefficient, β to the electron ionization coefficient, α, and M is multiplication gain. Which means, k becomes a figure of merit to describe the noise of the APD. Therefore, it is advantageous to utilize materials with low values of k. Recently, we reported a new kind of material AlInAsSb digital alloy, which has extreme low excess noise, the k value is as low as Si. In order to demonstrate the reason for the low excess noise, we design a series experiments, and verify some digital alloy materials can obtain better performances than same composition conventional materials.

Bio:

Yuan Yuan is currently pursuing his Ph.D. degree in Professor Joe C. Campbell’s group at University of Virginia, Charlottesville, VA. His research interests lie in the design, fabrication and characterization avalanche photodiodes (APDs), and single-photon detection.